Man-made boards used in the manufacture of articles such as interior paneling and exterior siding are often made of fiberboard, e.g., hardboard; chipboard; oriented strand board-fiberboard composites; particle board; oriented strand board-particle board composites; and the like. The intended visible major surfaces of these man-made boards are commonly embossed to provide a desired appearance, such as a pattern or grain. Commonly, the fiberboards are molded from a planar cellulosic mat to provide the desired embossment, and are laminated on or otherwise secured to a support structure, such as a frame.
Man-made boards are used in the manufacture of various articles, including doors, and more particularly, in the manufacture of door skins, or door faces, that are secured to opposite major surfaces of a door frame. The man-made door skins often are manufactured to simulate the appearance of expensive natural wood “multi-panel” doors. To accomplish this simulation, the door skins are provided with contoured depressions integrally connecting the simulated panels of the door skin to a major surface portion of the door skin. It is the contoured depressions, and their superior aesthetic qualities in particular, which, when appropriately manufactured, simulate the attractive milled appearance of a natural wood multi-panel door. One type of milled appearance, known as a bead-and-cove profile, is particularly popular.
FIG. 5 depicts in cross section contoured depressions of conventional door skins 100 having identical bead and cove profiles. Bead portion 101 generally refers to a convex portion of the exterior (upper in FIG. 5) surface of the contoured depression, whereas the cove portion 102 is represented by a concave region of the exterior surface of the contoured depression. A ledge 103 separates bead portion 102 and cove portion 102 from one another.
It has been found that the surfaces of the contoured molded depressions of conventional door skins 100 as depicted in FIG. 5 are very difficult to paint uniformly due to density differences generated during molding of the contours, and due to the confinement of the inclined surface areas within the relatively small, molded depressions. It has been found that variations in thickness of the molded article adversely affect paintability, causing the painted article to exhibit a non-uniform coat. Also, the contoured surface of the depression is extremely difficult to provide with embossments representing, for example, a wood grain pattern, because such embossed texture on depression-forming inclined walls has a tendency to cause the article to stick to the mold cavity, causing fibers to pull away from the surface of the molded article when it is removed from the mold cavity.
Articles possessing the profile of FIG. 5 also do not nest well with one another. Rather, adjacent stacked articles are characterized by sizable gaps between the articles, unless localized material removal is performed by post-molding processing. But localized material removal is time consuming and laborious, and generally inconsistent with high throughput production environments. Further, stacking instability can cause damage to the contoured depression profiles of the stacked articles, particularly in the exterior decorative surface areas of the lowermost articles. Damage often is the result of abrasive rubbing between the stacked articles experienced during shipping and handling. Loss of detail to the highly valued appearance of the contoured depressions can ruin the simulation of highly skilled millwork, and devalue the article.
The relatively large gaps between inefficiently stacked skins represent dead or wasted space. As a consequence, the number of articles that can be stably stored or shipped within a given volume of space, e.g., on a pallet or a truck bed, is much less than optimal. The wasted space raises production costs, particularly in relation to storage and pre-assembled palletized shipment of the stacked skins.
FIG. 6 illustrates the profile of another door skin 105. In FIG. 6 the non-uniform thickness is created primarily by the variations in thickness of the contoured area, e.g., bead portion 106 and cove portion 107, relative to horizontal planar wall 109. Bead and cove portions 106, 107 possess small thicknesses than planar wall 109. Because of their reduced thicknesses, bead and cove portions 106, 107 require a thicker paint coat than planar wall 109 to achieve a uniform paint appearance. In order to achieve a uniform, consistent paint appearance between the contoured area and planar wall 109 and simplify painting, the same thickness coat is normally applied to both the contoured area and planar wall 109. As a result, planar wall 109 receives an amount of paint in excess of that required to achieve paint uniformity at planar wall 109, thereby unnecessarily increasing labor and production costs. Further, the amount of paint applied to the entire exterior surface of skin 105 is dictated by the contoured area, e.g., 106 and 107, even though the contoured area constitutes a minority of the overall surface area of the exterior surface of skin 105. Furthermore, the increased thickness of planar wall 109 compared to the contoured area increases material costs and product weight without offsetting benefits.
The above-discussed problems of conventional molded composite articles are largely overcome by U.S. Pat. No. 5,543,234, the assignee of which is also the assignee of this patent application. The '234 patent discloses articles designed for efficient, essentially damage-free shipping and storage, while stacking articles one upon another. The articles include decorative molded walls characterized by depressions possessing convex and concave surface portions having inclined planar surface portions. An example of a depression profile of a skin 110 of the '234 patent is shown in FIG. 7. According to an embodiment of the '234 patent, when the articles are stacked on upon another, inclined planar surface portions 112, 114 establish multiple seating contact zones in the form of continuous planar interfaces between opposing surfaces of stacked articles. The multiple seating zones significantly reduce relative movement and abrasive contact between stacked skins. It is thereby possible to stack the articles, or skins, with stable nesting while preventing side-to-side rocking, surface abrasion, and damage, as otherwise encountered with conventional skins shown in FIG. 5 during long-haul shipping. Stacking of the skins depicted in FIG. 7 also can be achieved with relatively small gaps between the stacked skins, thereby reducing the amount of space required to store and ship skins. Additionally, the skins of FIG. 7 possess a substantially uniform density, and consequently require a low number of coats to achieve paint coating uniformity. Reductions in paint and painting labor time lower production costs.
The inclined planar surface portions of the articles disclosed in U.S. Pat. No. 5,543,234 provide an appearance with unique attributes desired by some consumers. However, other consumers might interpret the appearance of the inclined planar surface portions as manifesting a relatively contemporary architectural style, and therefore lacking of some of the historical millwork detail of a “bead and cove” Colonist design.
Therefore, it is desirous to combine classical design aesthetics and nestable functional elements in bead and cove molding geometries of a molded article having a substantially uniform density.